I love Perl, and I'm not afraid to admit it, but because it is such an easy to use language it is very easy to fall into some bad practices.

Damian Conway has written this excellent little guide to Perl best practices.

I don't agree with the order of what he suggests; mostly because I think most Perl programmers don't follow the model that would make it practical.

Top down development is great; mapping out and planning all of the different elements, but really, Perl makes it so easy to go bottom up and start adding features and functionality and then back-hack the system into a module and add testing and other bits that designing the module interface first is probably not going to work out the best way to go.